The present invention relates to a screw separator for separating solids out of suspensions, the screw separator comprising a housing and a suspension feed pipe, and a discharge for the separated liquids, and an outlet for the dewatered solids. The housing is provided with a strainer basket in which a screw is rotatably arranged.
These screw separators have become known from the prior art. For example EP 0 367 037 B1 discloses a screw separator in which the worm shaft is rotatingly mounted throughout the strainer basket and protrudes outwardly via the mouthpiece of the screw separator. The fact that the worm shaft extends outwardly through the mouth beyond the end of the strainer basket ensures that the slug forming by the action of the screw will retain its hollow cylindrical shape and will not collapse as the screw ends. As a rule a collapsing slug would provide a useless result since slug formation is a key prerequisite for this separation of solids out of the suspension.
The known screw separator is reliable in operation. One drawback is that the worm shaft rotating inside the slug is subjected to excessive abrasion due to the high relative speed between the substantially non-rotating slug and the worm shaft. The slug formed of solids tends to comprise abrasive substances resulting in a reduced service life of the screw.
It is therefore the object of the present invention over the described prior art to provide a screw separator which comprises reliability of function and increased durability.